John nebel



@N xw Q 1 e E E (No Model.)

J. NEBEL. 'ARMATURB FOR DYNAMO ELECTRIC MACHINES. No. 482,265.

Patented Sept. 6, 1892.

UNITED STATES JOI-IN NEBEL, OF CHARLTON, ASSIGNOR PATENT OFFICE.

THE SIEMENS BROTHERS & CO.,

LIMITED, OF WVESTMINSTER, ENGLAND.

SPECIFICATION forming part of Letters Patent No. 482,265, datedSeptember 6, 1892.

pp ion filed Novemherll, 1891. Serial No. 111,596. (No model.) Patentedin Germany February 22, 1891, No. 61.059; in England November 30, 1891,No. 20,840; in France December 24, 1891, N0. 2O i,633, and in BelgiumDecember 31, 1891,

To all whom it may concern.-

Be it known that 1, JOHN NEBEL, a citizen of England, residing at 35Maryon Road, Charlton, in the county of Kent, England, have invented newand useful Improvements in Armatures for Dynamo-Electric Machines, forwhich I have obtained a patent in Great Britain, dated November 80,1891, No. 20,840; in France, dated December 24,1891,No.201,683; inBelgium, dated December 31, 1891, No. 97,772, and in Germany, datedFebruary 22, 1891, No. 61,059,) of which the following is aspecification.

This invention relates to armatures of continuouscurrent dynamo-electric machines which are employed to give currents very large ascompared to the diameter of the armature. The conductors of sucharmatures must be of verylarge section and are usually copper bars ofrectangular section, solid, laminated, or stranded, arranged in a singlelayer around the periphery of the armature. Such machines are subject togreat sparking at the commutator and to great heating of the armature,resulting from eddy-currents set up in the bars, and the currents whichthey produce are of a very pulsating character.

The object of my invention is to reduce these evils, which I effect bycertain subdivision of the conductors, as I shall explain, referring tothe accompanying drawings.

Figure 1 shows diagrammatically the usual arrangement of conductors of adrum-armature. Fig. 2 shows the arrangement according to my invention.

Referring to Fig. 1, A indicates the rectangular copper bars, the curveddotted lines E indicate the connections at one end of. the drum, and thefull curved lines D indicate the connections at the other end of thedrum and to the commutatorsegments C.

B B indicate the brushes. As there are from brush B to brush B twoparallel paths, each barA has to carry half the total current producedby the machine. The diagram shows only twelve bars. When the number ofbars is increased, the objections still exist, though to a less degree.

Now according to my invention in dealing with an armature which has notless than eight conducting-bars I divide each of the conducting-barsinto two, three, or moresay 7tsections, and then add or subtract 2, 4,or 2n-2 bars, according as the conductors have been divided into two,three, or '22 parts, and I make the end connections andcommutatorsegments proportional to the number of bars. Each bar is thenconnected by the curved end connections, not to'the bar exactlyopposite, but to the second, third, or nth bar before the opposite one,according as the conductors have been divided into two, three,or nparts. Each brush is arranged to touch always two, three, or ncommutater-segments, according as the bars consist of two, three, or 92parts. The bars are thus connected in series or in one continuouscircuit over the armature, so that from brush to brush there are four,six, or two 77. parallel paths for current, and consequently each barhas to carry only one-fourth, one-sixth, or one-half nth of the totalcurrent. It, for instance, the original armature had twelve bars and itwere desired to divide each into two sections, making twenty-four bars,to this number there should be added two bars, making a total oftwenty-six; or, from twenty-four should be subtracted two bars, leavinga total of twenty-two. In like manner each of the twelve bars might bedivided into three sections, and then to the thirty-six so obtainedshould be added four bars, or from the thirtysiX should be subtractedfour, thus giving a total of forty or thirty-two bars.

Fig. 2 shows, diagrammatically, such an arrangement. for conductorsdivided into three sections, with four bars subtracted, making a totalof thirty-two bars and sixteen commutator-segments. In this case eachbar has to be connected by the curved end connections to the third barnext before the bar direct-1y opposite, following always the samedirection round the periphery. Thus the bar 1, to which 17 is directlyopposite, is connected through the n commutator-segments to 14. Again,11 has its end connection not to 30,directly opposite, but to 27, and soon. The brushes on each side never touch less than three segments.

In this case from brush to brush there are six parallel paths. Thereforeeach bar has to carry only one-sixth of the current.

It is an advantage of this arrangement as compared with a system ofindependent parallel circuits that it is quite symmetrical, whatever bethe number of the parallel circuits, requiring at both ends of thearmature exactly similar end connections, such as cannot always be usedwith independent parallel circuits.

I have described my invention applied to an armature having originallytwelve bars; but it is to be understood that the invention is applicableto armatures having more or less than twelve, but not less than eight,bars.

Having thus described the nature of this invention and the best means Iknow for carrying the same into practical effect,I claim An armature ofa dynamo-electric machine,

having its conducting-bars, not less than eight in number, divided intotwo, three, or 92 sections and this number increased or diminished byadding or subtracting 2, 4, or 2n 2, each bar of the number sodetermined being connected, not to that opposite to it, but to thesecond, third, or nth before the opposite, and each brush touching two,three, or n commutatorsegments, of which there are half as many as thereare bars, substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, this 16th day of October, A. D.1891.

JOHN NEBEL.

Witnesses:

GEO. P. SIMPsoN, M. THOMAS.

